Technical Field
The present disclosure relates to the field of organic light emitting display technologies, in particular to a pixel compensating circuit and method of compensating for voltage drop and drift occurring in the threshold voltage of an organic light emitting display device.
Technical Background
An organic light emitting display is a thin film light emitting device that is made of organic semiconductor material and driven by a direct voltage, and includes a very thin organic material coating and a glass substrate. Such organic material of the organic material coating can emit light actively when a current flows there through.
FIG. 1 is a schematic diagram showing a pixel driving circuit of an organic light emitting display in the prior art. A working process of the pixel driving circuit includes: a signal writing stage and a light emitting stage. In the signal writing stage, when a scanning signal Scan is at a high level, a transistor T12 is turned on to input a data signal Data to a gate electrode of a driving transistor T11 to turn on the driving transistor T11 to charge a capacitor C11; while in the light emitting stage, the scanning signal Scan is at a low level, the transistor T12 is hence turned off, the capacitor C11 enables the driving transistor T11 to be turned on, and a supply voltage signal PVDD continues providing a voltage for the organic light emitting display, until a next signal writing stage arrives. As such, the two stages repeats as above.
Since a light emitting luminance of the organic light emitting display depends on an amount of the current flowing through the organic light emitting diode, the light emitting luminance, as an electrical property of the driving thin film transistor, will directly affect an display effect of the organic light emitting display, and especially a threshold voltage of the driving thin film transistor often drifts, leading to an uneven luminance problem in the whole organic light emitting display.